The proposed research will utilize the recording of the electrical signals of the retina (Electroretinogram - ERG) and the cortex (Visually evoked potential - VEP) to investigate the human visual system in the normal and diseased state. A patterned stimulus will be used to elicit the ERG and VEP. The program will include: (1) The development of an objective electrophysiological test of cone dysfunction; (2) The investigation of the electrophysiological correlates of amblyopia; (3) The recording of visually evoked cortical potentials in infants as a means of studying visual development in normals and visual pathology in clinical cases; (4) The investigations of retinal and cortical mechanisms of color vision through the electrophysiological determination of increment thresholds.